_serializeFilter in cosmoz-omnitable-column does not serialize

[plequang]

Description

In cosmoz-omnitable-column, the function _serializeFilter from cosmoz-omnitable-column-behavior is overridden, and simply returns the filter object.

cosmoz-omnitable/cosmoz-omnitable-column.html

Lines 45 to 47 in ab73c90

	_serializeFilter(filter = this.filter) {
	return filter || null;
	},

This behavior is verified by a unit test:

cosmoz-omnitable/test/basic.html

Lines 130 to 136 in ab73c90

	test('_serializeFilter returns filter', () => {
	const column = omnitable.columns.find(col => {
	return col.name === 'columnWithGroupOn';
	}),
	filter = {key: 'value'};
	assert.deepEqual(column._serializeFilter(filter), filter);
	});

If this is really the desired behavior, there should be at least a comment that explain why this is so.

[megheaiulian]

In cosmoz-omnitable-column filter is a String. Because of that there is nothing to serialize, deserialize and we just need to check for falsy values ('', null, undefined).

[megheaiulian]

I think we should explicitly re-define the filter property as String in cosmoz-omnitable-column to make this a bit easier to understand.

[nomego]

Still an issue @megheaiulian ?